<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/animate.css/4.1.1/animate.min.css" />
  <style>
    .parent {
      width: 300px;
      height: 300px;
      background-color: #ccc;
      /* 水平居中 */
      margin: 0 auto;
      display: flex;
      align-items: flex-end;
    }

    .parent>div {
      width: 60px;
      height: 60px;
    }

    .parent>div:nth-child(2) {
      /* 设置自身在交叉轴对齐方式  
        flex-start/end center 
        baseline strecth
      */
      align-self: center;
    }
  </style>
</head>

<body>
  <div class="parent">
    <div class="div1" style="background-color:red;">弹性元素1</div>
    <div class="div2" style="background-color:green;">弹性元素2</div>
    <div class="div3" style="background-color: blue">弹性元素3</div>
  </div>
  <div style="width: 100px;height: 100px;background-color: red;" class="animate__animated animate__backInDown">我是animateDIV</div>
</body>

</html>